How to build Linear PSU?

[techmate]

Originally Posted by FauxFrench

A class A headphone amplifier, fine. 26V/0.8A I would make from a 30V/1.5A power adapter (SMPS), with 2200uF/50V at the output, followed by a linear post-regulator to reduce ripple and noise.

For the TP50 I would do the same but use a 9V/3A adapter instead.

ok sounds got, now i gotcha... let's make a list

[techmate]

Originally Posted by FauxFrench

A class A headphone amplifier, fine. 26V/0.8A I would make from a 30V/1.5A power adapter (SMPS), with 2200uF/50V at the output, followed by a linear post-regulator to reduce ripple and noise.

For the TP50 I would do the same but use a 9V/3A adapter instead.

will be nice if i could pack all togheter in one box which is going to be Psu box and from there cables that will feed dac and amp

[FauxFrench]

Originally Posted by techmate

will be nice if i could pack all togheter in one box which is going to be Psu box and from there cables that will feed dac and amp

Logically seen, keeping the linear regulators near the consumers (the class A headphone amp and the TP50) ensures better regulation for the power inputs. The two linear regulators may be arranged in one box. Then, the SMPS power adapters at a certain distance because they may radiate noise.
That is how I would do it.

[FauxFrench]

Originally Posted by jimk04

It works but I know it isnt correct!

I checked my DACMagic (Cambridge Audio) and I also feed it 12Vac to keep it happy. It is absolutely correct. The reason for the AC supply is probably that it is used to generate symmetrical supply voltages through single rectification. Then charge pumps are avoided.

[techmate]

Originally Posted by FauxFrench

Logically seen, keeping the linear regulators near the consumers (the class A headphone amp and the TP50) ensures better regulation for the power inputs. The two linear regulators may be arranged in one box. Then, the SMPS power adapters at a certain distance because they may radiate noise.
That is how I would do it.

i like you're idea, can you give me a hand in selecting all the parts that i need to accomplish the mission ?

Regards,

[FauxFrench]

Originally Posted by techmate

i like you're idea, can you give me a hand in selecting all the parts that i need to accomplish the mission ?
Regards,

I will, just give me some 6 hours to remove our old kitchen (my wife's orders!) and two hours more to draw the circuits.
I'll be back.

[jimk04]

Originally Posted by FauxFrench

I checked my DACMagic (Cambridge Audio) and I also feed it 12Vac to keep it happy. It is absolutely correct. The reason for the AC supply is probably that it is used to generate symmetrical supply voltages through single rectification. Then charge pumps are avoided.

Thanks for the reply.
I guess my comment was more directed at the fact that I just solely have the12v toroid and no other components.....no regulation or whatever. It is a 200VA job so shouldn't struggle to fees the DAC!

One question regarding the OPs situation....if we are to implement linear regulation to a DC supply....I can't find any ready made boards that can do 4 , 5, 6 Amps etc as may be required from a power amplifier.

Are there some out there I haven't yet landed on?

[FauxFrench]

Originally Posted by techmate

i like you're idea, can you give me a hand in selecting all the parts that i need to accomplish the mission ?
Regards,

My suggestion for a 26V/0.8A linear regulator and a 5V/3A linear regulator. I chose 2200uF/35V, 220uF/35V and 22uF/35V from the needs for the 26V regulator. That voltage rating is excessive for the 5V regulator where 16V would be sufficient. However, sometimes you do not buy capacitors by the piece but in lots of 10 and then it is more practical to use few different types.

With such post regulators the ripple and step response will improve compared to your present SMPS adapters. I chose for commonly available LM317 and LM338 because they perform well and are easy to get. You can find ultra low noise regulators that will need to be put in parallel to provide sufficient current. My unqualified impression, for which I will soon be battered, is that you will not notice the difference for the actual use.

[FauxFrench]

Originally Posted by jimk04

Thanks for the reply.
I guess my comment was more directed at the fact that I just solely have the12v toroid and no other components.....no regulation or whatever. It is a 200VA job so shouldn't struggle to fees the DAC!

One question regarding the OPs situation....if we are to implement linear regulation to a DC supply....I can't find any ready made boards that can do 4 , 5, 6 Amps etc as may be required from a power amplifier.

Are there some out there I haven't yet landed on?

You are right, 200VA should be more than sufficient. I use only the standard 18VA. Inside, Cambridge Audio probably does as shown on the schematic - turn the 12Vac into +/- 18Vdc, symmetrical supply voltages that are then regulated down to +/- 15V. I like that design much better than having a 5Vdc input and use charge-pumps (or a micro SMPS) to bring it to +/- 5-10V. To perform the best, many high quality OP-AMPS need +/- 12-15V.

I agree with you, linear regulator kits/boards for 3-8Amp are difficult to find. Most power amplifiers run from unregulated supply voltages.

A 3-8A linear regulator is rather simple so design with an LM317 or LM337 and a 15A buffer transistor controlled by the regulator. I have made one doing +/-16V-42V, 6A and work on a +/-2-15V/3A for low power experimental use. Using a suitable IC regulator chip makes design of a linear regulator rather simple. Only if you really know your circuits, discrete power supply constructions are worth considering.

[techmate]

Originally Posted by FauxFrench

My suggestion for a 26V/0.8A linear regulator and a 5V/3A linear regulator. I chose 2200uF/35V, 220uF/35V and 22uF/35V from the needs for the 26V regulator. That voltage rating is excessive for the 5V regulator where 16V would be sufficient. However, sometimes you do not buy capacitors by the piece but in lots of 10 and then it is more practical to use few different types.

With such post regulators the ripple and step response will improve compared to your present SMPS adapters. I chose for commonly available LM317 and LM338 because they perform well and are easy to get. You can find ultra low noise regulators that will need to be put in parallel to provide sufficient current. My unqualified impression, for which I will soon be battered, is that you will not notice the difference for the actual use.

thank you very much you did an excellent job, will be so nice if i could print a pcb and then solder the stuff on it....ooo dreamin'.....